explain xkcd - User contributions [en]

2859: Oceanography Gift

2023-11-25T19:49:35Z

172.71.178.68: /* Explanation */ Revamps

{{comic
| number = 2859
| date = November 24, 2023
| title = Oceanography Gift
| image = oceanography_gift_2x.png
| imagesize = 740x272px
| noexpand = true
| titletext = Shipping times vary. Same-ocean delivery may only take a few years, but delivery from the Weddell Sea in Antarctica may take multiple decades, and molecules meant for inland seas like the Mediterranean may be returned as undeliverable by surface currents.
}}

==Explanation==
{{incomplete|Created ten years ago by a WATER CURRENT - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
In this comic, [[Randall]] seems inspired by the timing of {{w|ocean current}}s, much as he has previously been with [[2805: Global Atmospheric Circulation|air currents]], although he may even have already considered some of the technicalities [[1675: Message in a Bottle|prior to that]]. As supporting evidence, he provides a DOI reference to a 2016 Jönsson & Watson open-access article in Nature Communications, '[https://www.nature.com/articles/ncomms11239 The timescales of global surface-ocean connectivity]'.

In this specific (fictional) example, the water dumped into the ocean today will take ten years to circulate round to the depicted neighbouring coastline (wherever that is). Which implies significant planning ahead is necessary before posting water to someone. And a lot of presumption about the lack of any other dispersal/dilution, or that some degree of fungibility is acceptable, so long as it is ''{{w|Ship of Theseus|philsophically}}'' the same group of molecules involved.

The title text mentions that "same-ocean delivery" may only take a few years, as the coast lines are in the same general body of circulating water, and doesn't have to pass around large obstacles (like continents) or through small gaps (straits). But if you wish delivery from {{w|Weddell Sea}} it may take decades. The Weddell lies near the {{w|Antarctic Peninsula}}, part of the {{w|Southern Ocean}} whose circulation can be considered largely isolated from the neighbouring bodies of water by the {{w|Antarctic Circumpolar Current}}. In particular, that area contains the {{w|Weddell Gyre}} one of the two {{w|ocean gyre}}s in that area.

The title text also mentions {{w|inland sea}}s, which can be generalised as bodies of water that are very large in area but either completely surrounded by dry land or connected to an ocean only by a river or a strait. He mentions the {{w|Mediterranean Sea}} which is only connected to the {{w|Atlantic Ocean}} through the narrow {{w|Strait of Gibraltar}}; the intention of the title text is to suggest that water molecules dumped in an ocean would not get to appear in such a sea (except by {{w|evaporation}} and re{{w|precipitation}}) into its catchment area) and thus they can only ever circulate back to the dumping point (deemed 'undeliverable').

In reality, the Mediterranean Sea is not completely cut off from the main oceans and surface currents actually do reach into and around the Mediterranean. The natural loss from evaporation is not fully compensated for by the inflow of the incident rivers from southern Europe, North Africa and Asia, directly or via other attached bodies of water (e.g. the Black Sea). The movement of water also involves the deeper Levantine Intermediate Waters layer (a subsurface current) which exits via Gibraltar and helps to further draw current inwards at the surface level. As such, except for a limited amount of water which reverses direction within the extreme western end the Mediterranean, it is more true to say that ''surface'' currents cannot actually transport water from within the sea outwards into the Atlantic (and beyond).

The {{w|Caspian Sea}} is a real inland sea that has no outlet to any oceans and only inlets from rivers, one of many [[2325: Endorheic Basin|endorheic basins]] that are also lakes, and thus trivially isolated from all other maritime currents.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.|Probably still improvable}}

:[Cueball and Megan are standing thigh deep, at either edge of a stretch of water between two steep but walkable shorelines.]

:[Cueball, at the left, is apparently opening bottles of water and pouring them into the sea while recording himself.]
:Cueball: Happy birthday!
:Cueball: I got you these water molecules.
:[Sound effects:] (click) (pour)

:[The water between has a morass of short swirling arrows indicating movement. In the air above this there is a square-bracketted 'label']
:[Label:] 10 years pass 

:[Megan, at the right, is dipping bottles into the water to fill them]
:Megan: Aww, thank you!
:[Sound effect:] (scoop)

:[Text below comic:]
: Global surface ocean connectivity times are ≤10 years (Jönsson & Watson, 2016, DOI:10.1038/ncomms11239), so if you're willing to plan ahead, you can pour water into the ocean while wishing someone a happy birthday, and then in 10 years let them know they can pick up their gift at the nearest coastline.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with lowercase text]]

Talk:2856: Materials Scientists

2023-11-22T23:13:09Z

172.71.178.68:

It isn't "amarid", it's "[https://en.wikipedia.org/wiki/Aramid aramid]"... -- [[User:Dtgriscom|Dtgriscom]] ([[User talk:Dtgriscom|talk]]) 03:03, 18 November 2023 (UTC)
: Sounds like a great case for a "Trivia" section below the transcript. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 23:19, 18 November 2023 (UTC)

Damn, I'd love some gift wrap like that, it sounds fascinating, and I'm not even a materials scientist. [[Special:Contributions/172.70.130.91|172.70.130.91]] 08:29, 18 November 2023 (UTC)

Whoever added "This comic may also be an example of nerd sniping." should have said what the "nerd sniping" is that they detect here. Giving us terms to look up? Certainly not the spelling error, that's just a simple mistake. "Looking up" doesn't seem like enough to qualify, it should to be a problem to figure out, a solution begging to be found. I'll give it some time, but if I don't see this claim properly expanded I'll remove it next time I'm here. [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 06:32, 19 November 2023 (UTC)

:There's some editing conflict over that point. It seems obvious to me that there's no "nerd sniping" here since the "nerd" isn't being put in danger. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 16:56, 22 November 2023 (UTC)

::I agree with you, Bunsen, but if you look at the original nerd sniping comic's title text, Randall got nerd sniped but he wasn't actually in danger though. In a later talk (at Dartmouth?) he talks more about this. After looking into that I think they should leave the nerd sniping connection in the explanation. [[Special:Contributions/172.69.65.156|172.69.65.156]] 18:50, 22 November 2023 (UTC)

When I was in high school chemistry way back in 1960 or so, we used to make Nitrogen Triiodide. It is extremely easy to make — put some crystals of iodine in a filter paper in a funnel. Pour ammonia over them. Let dry — often the triiodide will explode as it dries. If scattered on the floor, it will explode if someone steps on it. The explosion is accompanied by a puff of purple smoke.
[[Special:Contributions/172.70.135.17|172.70.135.17]] 12:02, 20 November 2023 (UTC)

Is there any relationship between Materials Scientists and {{w|Material Girl}}s? --[[Special:Contributions/188.114.102.34|188.114.102.34]] 16:29, 20 November 2023 (UTC)
:Well, they're both living in a Material World.[[Special:Contributions/172.69.195.174|172.69.195.174]] 16:24, 21 November 2023 (UTC)

Is anyone else getting a HUGE image for this comic? It's showing up as a 4437 × 6680 pixels, 1200DPI, RGB image too big for the browser. I had to "open image in another tab" to view the whole thing. For comparison, the next comic is only 328 × 437 pixels, 80DPI, Gray. [[Special:Contributions/162.158.146.233|162.158.146.233]] 04:47, 22 November 2023 (UTC)
:Yeah, same issue here with the dimensions. It wasn't showing up that way when it was first posted, either. [[Special:Contributions/172.71.147.130|172.71.147.130]] 09:31, 22 November 2023 (UTC)
::Probably he reuploaded with a correction from "amarid" to "aramid" [[Special:Contributions/198.41.236.148|198.41.236.148]] 11:11, 22 November 2023 (UTC)
::Yes, Randall updated the comic image with the correction, but uploaded the wrong size. I downloaded the large image and resized it to match the original 2x image here, then uploaded the new version of it over the original image. The cache appears to have finally updated, and this corrected image should now be visible to everyone here. [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 15:16, 22 November 2023 (UTC)

Should the stuff about the "amarid" misspelling be moved to something like a "Trivia" section now that the comic has been corrected? [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 16:56, 22 November 2023 (UTC)
:Typically, yes. With link to original image for those who want to look at the prior version ...if the new (rescaled) "aramid" one has indeed been made to replace the "amarid" original, you can link to the appropriate 'diff=' page. But it's probably an edit that can wait until someone willing to do it is doing some other tweaking, generally. There'll be something else, there's ''always'' something else. ;) [[Special:Contributions/172.71.178.68|172.71.178.68]] 23:13, 22 November 2023 (UTC)

Talk:2854: Date Line

2023-11-19T14:38:16Z

172.71.178.68:

The 'standard' and '2x' sized images had unexpected sizes, so a Trivia section has been automatically generated, and an imagesize parameter has been added (at half size) to render the image consistently with other comics on this website. --[[User:TheusafBOT|TheusafBOT]] ([[User talk:TheusafBOT|talk]]) 22:56, 13 November 2023 (UTC)
: I see no evidence of this, so the Trivia section should probably be removed. The comic appears standard sized on XKCD (both in the page and if opening the direct link), and the link in the Trivia also leads to a standard size image. [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 04:19, 19 November 2023 (UTC)
:: Things have been known to be corrected. For whatever reason, TheusafBOT detected the initial issue (since it was made to do so, these problems recently having occured in other comics and caused problems) and it certainly ''was'' worth the automatic note making to make people aware of the (probable) discrepancy.
:: Without looking into possible webarchived material, or delving too deep into the current stock, I think it's worth keeping a small note (just as when the original "neeeded" was corrected to "needed" in a title text, etc), but obviously reword it as being no longer true (and/or change link to the erroneous size's archive location, if there is one?). I would also then see no problem with fully excising the 'BOT announcement here (and your response and this response to that) here on the Talk page.
:: If you'd prefer to excise the "Trivia", then I suggest transfer the gist (not header) here to Talk as a quote/indent, so future readers know what we're talking about, and leave this part of the fuss intact. (Same for any other such 'corrected' anomolies you can find needing sorting out in other comics, albeit their Talk elements are probably thankfully unaugmented by this particular metaⁿ-discussion.)
:: I'm sure if you edit it all how you want to, though, it'll all be critically assessed by every other editor who cares (myself, I care little about this particular issue, just 'best wiki-keeping practices' in general, not liking to lose information that has been 'true') and modified/whatevered at ''their'' whim, just as we gladly honour/humour your own edits.... ;) [[Special:Contributions/172.70.85.208|172.70.85.208]] 14:32, 19 November 2023 (UTC)
:: Meant to add: the "evidence" for it is in the following comments, editors who witnessed this. Which is good enough for me to be a fact (and not even a {{template|fact}}). [[Special:Contributions/172.71.178.68|172.71.178.68]] 14:38, 19 November 2023 (UTC) (aka 172.70.85.208, above, in case that has changed)
Is it just me or are these size errors becoming more common? What going wrong in the infra?
[[Special:Contributions/172.69.62.90|172.69.62.90]] 22:57, 13 November 2023 (UTC)

:Yeah, and this one came in HUGE. The image size upon loading the comic at xkcd.com was 6642x7838. At first, I thought it was a special comic or an interactive one. But just huge. [[User:Orion205|Orion205]] ([[User talk:Orion205|talk]]) 00:25, 14 November 2023 (UTC)

added an explanation [[Special:Contributions/172.70.174.61|172.70.174.61]] 23:49, 13 November 2023 (UTC)

The IDL might not normally be straight, but when the rocket pulls in it, it will straighten it out. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 00:54, 14 November 2023 (UTC)

The Kentucky State Police resent the implication about their organizational infrastructure.

I like how this comic came out the same day (in UTC+10) as I am studying Earth geometry including the IDL. Nice little coincidence. [[User:OmniDoom|OmniDoom]] ([[User talk:OmniDoom|talk]]) 03:46, 14 November 2023 (UTC)

Why's there a missing line of latitude? [[Special:Contributions/172.68.140.145|172.68.140.145]] 05:47, 14 November 2023 (UTC)
:That is actually a good question. Seems like an error. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 08:01, 14 November 2023 (UTC)
: I would assume the lines that are shown are intended to be the equator, tropics, and arctic circle (antarctic being hidden out of view), being the most commonly known lines of latitude.[[Special:Contributions/172.70.85.151|172.70.85.151]] 12:04, 14 November 2023 (UTC)
:: The latitude lines, the top one is obviously the Arctic Circle. The next goes through the northern part of Africa, making it the Equator. Next would be a Tropic. Where's the northern Tropic? (I always mix up Cancer and Capricorn, I want to go with Cancer). Missing line. [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 04:19, 19 November 2023 (UTC)
:I think it's just the angle. If viewed from the side (instead of diagonally above as in the image), I think they would appear more equidistant. Or maybe they're based on a different projection entirely, that wouldn't be out of character for Randall either. [[Special:Contributions/172.70.46.254|172.70.46.254]] 12:08, 14 November 2023 (UTC)
:: No, the northern Tropic is missing. After Arctic it shows the Equator, there should be a Tropic in between. [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 04:19, 19 November 2023 (UTC)

Even if the lines were actual physical strings/ropes, they appear to be lying right on the earths surface instead of being suspended in mid air. So how would a rocket accidentally get snagged on one? You'd have to purposefully shove the rocket between the earth and the line before launch. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:39, 14 November 2023 (UTC)
:Well, obviously you wouldn't want ships/trains/etc hitting them as they moved longitudes(/latitutudes) or timezones, so they must be held up out of the way by skyhooks. Probably also above plane travel, or we'd see them being snagged quite often...
:Noting that I had to caveat the idea of the Russian launch-site, as NASA seems to be the named agency needing to fix the mess. Could of course be 'Hollywood Exceptionalism', regarding who it is who <s>leads</s> saves the world. Or ''actual'' expertise such as might have actually helped with the Kursk submarine, in a pinch (except that, geoplitically, currently it'd probably take even longer for Russia to deign to request assistance from the US than 23 years ago).
:I also, for brevity, skipped the needless pedantic analysis of typical 'first orbit' trajectories from ''all'' [https://aerospace.csis.org/data/spaceports-of-the-world/ current launch sites], worldwide, so as to work out whether any others might encounter such a North Pacific crossing-point at 'first hit' (after which, it's clearly high enough to not snag again). Depending on launch eccentricity, it's feasible from practically any of them, naturally. [[Special:Contributions/172.69.195.51|172.69.195.51]] 10:37, 14 November 2023 (UTC)

:Maybe it was a submarine launched rocket.[[Special:Contributions/172.70.86.53|172.70.86.53]] 12:06, 14 November 2023 (UTC)

:It's obviously North Korean. Russia disclaims any involvement. [[Special:Contributions/172.71.102.143|172.71.102.143]] 08:42, 15 November 2023 (UTC)

I think the "about 2 in the title text references the Windows approximate download times dialogs - GreyFox [[Special:Contributions/172.71.150.133|172.71.150.133]] 18:31, 14 November 2023 (UTC)
:It's not. They were about to say an absolute time, e.g. "by approximately 12:00" but they realized absolute time is paused so they gave a relative time instead. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 22:39, 14 November 2023 (UTC)

This looks devastating for western Europe and western Africa. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 22:39, 14 November 2023 (UTC)

I just tripped over the 90º24’ line. What is with these new strings? [[User:TenGolf MathHacker|TenGolf MathHacker]] ([[User talk:TenGolf MathHacker|talk]]) 15:12, 15 November 2023 (UTC)

Talk:2829: Iceberg Efficiency

2023-09-15T13:26:53Z

172.71.178.68:

BH clearly isn't Freudian. For the {{w|File:Structural-Iceberg.svg|Iceberg of the Mind}}, the most important part is the 90% of it that is ''hidden''. Which makes for a totally ''different'' (and potentially more implementable) solution whenever you happen to consider that the most important function of an iceberg is to sneak up on ships... ;) [[Special:Contributions/172.71.178.68|172.71.178.68]] 13:26, 15 September 2023 (UTC)

2172: Lunar Cycles

2023-03-15T22:43:09Z

172.71.178.68: more exact link to "blood moon" (Wikipedia)

{{comic
| number = 2172
| date = July 5, 2019
| title = Lunar Cycles
| image = lunar_cycles.png
| titletext = The Antikythera mechanism had a whole set of gears specifically to track the cyclic popularity of skinny jeans and low-rise waists.
}}

==Explanation==

This comic shows a mixture of real, scientific lunar cycles and cycles that are comedic or fictional in nature. The first four cycles are factual, while the ones following them are not.

*'''Nodal precession:''' The Moon's orbital plane is tilted slightly compared to the Earth's orbital plane around the sun (the {{w|ecliptic}}). This tilt is why we don't constantly see eclipses; most of the time, the Moon's orbital plane is tilted higher or lower than the Sun, so they generally don't cross each other. The two points at which these planes ''do'' cross are called {{w|lunar nodes}}. {{w|Nodal precession}} is the gradual rotation of these nodes over time, a gyroscopic consequence of Earth's equatorial bulge. For the Moon this follows an 18.6 year cycle.

*'''Apsidal precession:''' All orbits have two points where the orbiting body is either closest to, or furthest away from, the thing they are orbiting. These points are called {{w|apsides}}, and the imaginary line between them is called the ''line of apsides''. {{w|Apsidal precession}} is the gradual rotation of this line over time, which occurs in cycles of around 8.9 years for the Moon.

*'''Phase:''' {{w|Lunar phase}} describes the change in shape of the sunlit side of the Moon as viewed from the Earth's surface, which is caused by the changing angle between Moon and Sun as the Moon revolves around the Earth. The cycle of lunar phases takes 29.5 days, a figure referred to as the ''synodic month''.

*'''Distance:''' Because the Moon's orbit around the Earth is elliptical, its distance from the Earth varies slightly over the course of an orbit. This means that the moon's distance also follows a cycle which is the same as the length of one lunar orbit: approximately 27.5 days. This figure is referred to as the ''anomalistic month''. Note that the synodic month is (perhaps counterintuitively) two days ''longer'' than the sidereal month — or to put it another way, it takes 2 more days for the Moon's phases to cycle than it does for the Moon to go around the Earth. This is due to the fact that the Earth is also moving ''around'' the Sun while the phases are going on, which means that the Moon has to spend 2 extra days "catching up" to the point at which the lunar phase cycle can restart.

*'''Earth-Moon relative size''': This is a joke cycle; the Earth and Moon do not physically change size, nor does the Moon ever become larger than the Earth. This may be playing on the idea that the Moon often ''appears'' to change size to viewers on Earth, due to various factors; most commonly, this is due to the {{w|Moon illusion}}, which tricks the brain into perceiving the Moon as much larger than it really is. There are also so-called {{w|supermoon}}s, which occur when the full moon coincides with the Moon's closest approach to Earth; these actually do increase the Moon's apparent size, although by a relatively insignificant amount.

*'''Lunar shape:''' Again, this is a joke cycle; the Moon does not actually change shape. A shape intermediate between circle and square is known as a {{w|squircle}}, a subclass of the {{w|superellipse}}.

*'''Lunar mood:''' The moon does not have a mood, although humans can have moods that fluctuate over time, sometimes with a regularity akin to a cycle. Ironically, the section of the graph that shows a good (i.e. happy) mood has the graph line curving up then down like the mouth of a frown, and for the bad (unhappy) mood it curves down and then up, as in the mouth of a smile.

* The final diagram shows many different cycles superimposed on each other, highlighting areas where several cycles are coinciding. This is likely satirizing the media trend of overhyping astronomical coincidences and giving them grand-sounding names:
:*The light gray "phase × distance" plot does not correspond to the product of periods given for phase and distance, which [https://i.imgur.com/0i0mcPn.png look like this] instead.
:*A [[wikipedia:harvest moon|harvest moon]] is the traditional name for the full moon closest to the autumnal equinox, but there is nothing astronomically significant about it.
:*A [[wikipedia:Supermoon|supermoon]] is a full or new moon when the Moon is closest to the Earth, resulting in a slightly larger-than-usual apparent size. A full supermoon is roughly 14% larger in diameter than when the Moon is furthest away. See also [[1394: Superm*n]].
:*A [[wikipedia:blue moon|blue moon]] was originally a description of the very rare occurrence of atmospheric conditions that gave the Moon a bluish tinge, hence the expression "once in a blue moon" for something that happens only rarely. However, the actual blue-hued appearance of the moon is so rare that it the phrase "blue moon" has been reinterpreted as referring to a merely uncommon event: the occurrence of two full moons in a single calendar month. That kind of "blue moon" naturally does not look any different from a regular full moon.
:*A [[wikipedia:Blood Moon (eclipse)|blood moon]] refers to the moon during a lunar eclipse.
:*While the popularity of '''skinny jeans''' ([[wikipedia:Slim-fit pants|slim-fit pants]]) does change over time, the idea that this is connected to a lunar cycle is also a joke.
:*The [[wikipedia:Golden Age of Television|Golden Age of Television]] is said to have occurred in the 1940s and 50s, and the 2000s.
:*'''Pork''' {{w|Mooncake|'''moon'''cakes}} have been prepared in the rural areas west of Shanghai since more than a thousand years ago, for the Chinese {{w|Mid-Autumn Festival}}.
:*[https://scryfall.com/card/m20/120/vampire-of-the-dire-moon "The Vampire of the '''Dire Moon'''"] is a recently introduced, uncommon card from the {{w|Magic: The Gathering}} card game.
:*{{w|Astrology}} is a pseudoscience which claims that the positions of the celestial bodies can be used to predict human affairs. The chart jokingly suggests that astrology actually ''does'' work, but only within a very specific two-week timeframe.
:*Finally, while the idea of a '''total eclipse of the sea''' seems absurd, [https://www.deepseanews.com/2017/08/what-happens-in-the-sea-during-a-solar-eclipse/ an eclipse was famously used to explain the migration of maritime animals]:
:::''biologists were beginning to unravel the mystery of this ‘false bottom’–a layer in the ocean that looks the the sea floor on the sounder but isn’t–which covered much of the ocean. This false bottom rises in up at night and sinks down during the day. This rising and falling is in fact caused by the largest migration of animal on Earth–everything from fish, shrimp and jellyfish, moving hundreds of meters in unison up and down each day.... the moon moved into its place in front of the sun, daylight rapidly faded, and the scientists solved the migration mystery: the deep layer of animals began to rise. Bioluminescent creatures started to shine, and nocturnal creatures started a frantic upward thrust. As the world grew darker, they swam upward nearly 80 meters. But this frantic migration didn’t last long. As the moon receded and the sun revealed itself, the massive animal layer did an about-face, scrambling back into the safety of the darkness.''
:: (Backus, Clark, and Wing (1965) [https://sci-hub.tw/10.1038/205989a0 "Behaviour of certain marine organisms during the solar eclipse of July 20, 1963"] ''Nature'' '''4975:'''989-91.)
The '''{{w|Antikythera_mechanism|Antikythera mechanism}}''' mentioned in the title text is an ancient Greek machine, rediscovered in 1901, designed to calculate astronomical positions. The title text jokes that there is a set of gears on said mechanism that is used to predict the popularity of "skinny jeans" and "low-rise waists." Since it was likely created in the 1st or 2nd century B.C., it is impossible for the creators to have had any knowledge of skinny jeans or low-rise waists - both are modern-day clothing fashions{{citation needed}}.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:Understanding lunar cycles

:Nodal precession
:[A diagram showing a broad cosine-like wave with wavelength labelled as 18.6 years. To the right are two diagrams showing an orbital cycle moving in and out of plane.]

:Apsidal precession
:[A diagram similar to the one above but with a slightly shorter wavelength, labelled as 8.9 years. To the right are two diagrams showing an elliptical orbit around a planet and the same orbit rotated.]

:Phase
:[A diagram similar to those above with a shorter wavelength, labelled as 29.5 days. To the right is a diagram showing four phases of the moon: New, Waxing crescent, Waxinf gibbos, Full.]

:Distance
:[A diagram similar to those above with a shorter wavelength, labelled as 27.5 days. To the right is a diagram showing the distance of the moon from the Earth over time, with distances marked by arrows.]

:Earth-Moon relative size
:[A wave with long wavelength with an arrow pointing to the minimum labelled 'Earth bigger' and an arrow pointing to the maximum labelled 'Moon bigger'. To the right are two diagrams of the moon and Earth, one showing the Earth bigger than the Moon and the other showing the Moon bigger than the Earth.]

:Lunar shape
:[A wave with long wavelength with an arrow pointing to the minimum labelled 'Circle' and an arrow pointing to the maximum labelled 'Square'. To the right is a diagram showing a circle, a circle transforming into a square with outward arrows at each corner and a square transforming into a circle with inward arrows.]

:Lunar mood
:[A wave with long wavelength with an arrow pointing to the minimum labelled 'Bad' and an arrow pointing to the maximum labelled 'Good'. To the right are four emojis: :), :|, :(, :|]

:[A superimposed graph of all the above waves. Different points on the graph are labelled: Harvest moon, Supermoon, Blue moon, Skinny Jeans popular, Super blood moon, Golden age of TV, Dire moon, Pork moon, Two week window in which astrology works, Total eclipse of the sea.]

[[Category:Astronomy]]

{{comic discussion}}